The general purpose of the research is to elucidate the mechanisms of intestinal absorption and secretion, with emphasis on fluid secretion. It is proposed to extend our previous studies of the passive permeability of the dog small intestine, and of pressure induced intestinal secretion. An attempt will be made to clarify the mechanism of the intestinal secretion associated with intestinal obstruction. An attempt will be made to develop an isolated perfused secreting rabbit vermiform appendix preparation.